Atmospheric chemistry of expected nitrogen heterocycle emissions from oil shale operations.

摘要

U.S. oil shale reserves may have to be exploited in the future to ease dependence on foreign energy supplies. Development of oil shale, and many other synthetic fuel sources, will present new environmental problems. One of the major concerns of oil shale retorting is the large quantities of aqueous waste (retort water) and solid waste (spent shale) that will require disposal. Codisposal of these two waste streams has been proposed as the most likely disposal scenario. Codisposal will result in atmospheric emission of the volatile compounds present in the retort waters. The volatile emissions will probably be dominated by alkylsubstituted nitrogen heterocycles, particularly the alkylpyridines.; To predict the effect of these volatile emissions on areas downwind of oil shale facilities, it will be necessary to understand the atmospheric physical and chemical behavior of the compounds being emitted. To date, the atmospheric behavior of the alkylpyridines has not been investigated. The purpose of this work was to determine the kinetics of the most likely atmospheric chemical reactions for a group of alkylpyridines. Knowledge of these kinetics allowed for estimation of the atmospheric lifetime of each compound based on an assumed set of conditions.; Experimental and empirical procedures were used to estimate kinetic coefficients for three possible routes to tropospheric degradation of a group of alkylpyridines. Three experimental procedures were used to estimate photochemical degradation rates. An existing procedure was modified to estimate reactions between the alkylpyridines and ozone, with each of the individual reactions assumed to be elementary and bimolecular. Kinetic coefficients for the hydroxyl radical-alkylpyridines reactions were estimated using an empirical procedure. Attempts at estimating these kinetic coefficients experimentally were unsuccessful.; The tropospheric chemical behavior of each of the alkylpyridines was found to be dominated by hydroxyl radical reactions. These reactions will likely determine the lifetime and chemical fate of the alkylpyridines in the atmosphere. Of the alkylpyridines investigated, the atmospheric lifetimes were found to be less than 30 days; lifetimes decreased as the degree of alkyl-substitution on the pyridine ring increased.